I think I got it, but I'd like a second opinion. Literally I think it's something like "If you stand on your head, your skin tone is just like Akagi-san's." But I'm fairly certain the headstanding is figurative (like 逆立ちしても is literally "even if you stand on your head" but basically means "no matter how hard you try").
Zuikaku...You don't look so good, are you okay?!Don't be too concerned about it...What happened Shoukaku-nee?!Actually, today, Kaga-san...Onee-chan was scared......is what she...Your skin looks just like Akagi-san's, you know?Shoukaku... If I squint a little...